Electrosurgical pencil

ABSTRACT

An extendable electrosurgical pencil adapted to receive an electrode controllable by an electrical signal for performing surgical operations, including a housing that comprises first and second housing parts with a main housing part therebetween, a flexible printed circuit, a switch on the main housing part that is adapted to be activated from outside the housing for closing the flexible circuit, and an electrode receiver on the first housing part, wherein the first housing part is adapted to slide inside the main housing part to provide a telescopic extension of the pencil, the electrode and the flexible printed circuit following the sliding movement.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.15/868,926 filed Jan. 11, 2018, which is a division of U.S. patentapplication Ser. No. 14/487,447 filed Sep. 16, 2014, now U.S. Pat. No.9,901,391 B2, which is a division of U.S. patent application Ser. No.14/114,476 filed Oct. 28, 2013, now U.S. Pat. No. 8,858,550 B2, which isa 371 filing of International patent application No. PCT/DK2012/050176filed May 18, 2012, which claims priority to Danish patent applicationno. PA 2011 70251 filed May 19, 2011.

BACKGROUND

The invention relates to an electrosurgical pencil adapted to receive anelectrode controllable by an electrical signal for performing surgicaloperations, comprising: a housing, a circuit, switching means adapted tobe activated from outside the housing for closing the circuit, whereinthe housing comprises receiving means (for receiving the electrode. Theinvention further relates to a kit of parts comprising anelectrosurgical pencil and a method of providing an electrosurgicalpencil and a kit of parts.

Electrosurgical pencils are used during operations for, for example,cutting in tissue or coagulating blood by delivering a high voltage,high- or radiofrequency current from a source of electricity to anelectrode of the pencil. Depending on the waveform of the current, thepencil has a cutting or coagulating effect on the tissue. Some pencilsare provided with means for evacuating smoke from the operation site asthe smoke is known to contain viral DNA, bacteria, carcinogens andirritants.

Generally, electrosurgical pencils are constructed of two elongatehousing parts assembled lengthwise, one of which is provided with holefor accommodating control buttons. The pencil is at the forward endprovided with a bore, through which an electrode/blade projects. Fromthe rearward end a cable extends from an aperture. The cable isconnected to a printed circuit board inside the housing.

Such a pencil is known from US 2009/0062791. This pencil furthercomprises a switch module, comprising the printed circuit board uponwhich two dome switches are positioned. The buttons are located abovethe respective dome switches. A resilient sleeve encloses the printedcircuit board and the dome switches inside the housing. The resilientsleeve acts as a gasket to prevent the escape of low pressure air fromthe interior of the housing at the buttons, and to prevent the smoke andother debris from contaminating the switches. A wire conducts a radiofrequency electrosurgical waveform from the printed circuit board to anelectrode anchor unit. The anchor unit comprises several conductiveelements.

Another such pencil is known from U.S. Pat. No. 4,625,723. Here, aresilient strip of electrically conductive metal or alloy connects theelectrode and the printed circuit board. Push buttons under which a domemember and a metal disc are provided, bridges contacts to the printedcircuit board when the button is pushed.

Though pencils of this kind are widely used, they suffer from a numberof disadvantages, among others the large number of different parts thatare used complicate the production process and the many parts cluttersthe limited space available in the pencil so the space cannot be used toprovide an effective suction channel. Additionally, the many parts makethe device larger and not particularly comfortable to work with.

SUMMARY OF THE INVENTION

The invention now provides an electrosurgical pencil with improvedenergy transmission and a simple construction that eases the productionprocess considerably. This is achieved with a flexible printed circuit,wherein the flexible circuit is positioned such that the flexiblecircuit is in direct contact with the electrode, when the electrode ispositioned in the receiving means.

An electrosurgical pencil is provided which is adapted to receive anelectrode controllable by an electrical signal for performing surgicaloperations, comprising: a housing, a circuit, switching means adapted tobe activated from outside the housing for closing the circuit, whereinthe housing comprises receiving means for receiving the electrode, Ifthe circuit is a flexible circuit, the flexible circuit is positionedsuch that it is in direct contact with the electrode, when the electrodeis positioned in the receiving means.

By positioning the circuit in direct contact with the electrode, abetter contact between the electrode and flexible circuit is provided asno intermediate elements are required. Additionally, the construction issimpler and requires fewer steps in the production of the pencil.Usually, a metal bushing would be required, but now the receiving meanscan be provided in the same material as the main housing part where thereceiving means may be located. Furthermore, the pencil is lesscluttered on the inside and thereby opens up for the possibly ofintegrating a suction channel, while at the same time keeping the pencilslim and easy to handle. The advantage of the flexible circuit is thatonly one switch is activated when the flexible circuit is indirectlypressed. In case of a less flexible circuit, such as a printed circuitboard, all switching means would be activated when the circuit ispressed, as the pressure would be distributed and hence applied to allthe switches below the circuit.

The flexible circuit may further comprise a first portion and a secondportion, wherein the second portion is substantially parallel with thefirst portion, when mounted in the housing. By bending the flexiblecircuit and making the two portions parallel in the mounted position,the complete flexible circuit does not have to be integrated in thereceiving means and thereby the housing parts are easier to produce.

The housing comprises a sheath in a soft and resilient material, whichsheath encloses mainly the main part of the housing and the sheath hasactuators that are integral with and protrude from said sheath.

The switching means may comprise a switch and the actuator. Dividing thefunctionality between the switch and the actuator improves theflexibility of design and ease of manufacture even further. In preferredfurther developments of this embodiment, the first portion of theflexible circuit is positioned between the actuator and the switch, andthe back of the switch is facing the actuator. By turning the switch soto speak upside down, the flexible circuit together with the actuatorprovides two layers of insulation without using an extra material layer.Additionally, this position of the switch gives a better response to theuser and makes the actuator easy to press so that the switch isactivated even if only the edge of the activator is pressed.Furthermore, a more resilient material may be used for the actuators.

The housing may comprise a sheath, wherein the thickness of the sheathis greater than 0.35 mm in the area of the switching means. Thethickness provides a better protection in general and against tearing inparticular.

At least a part of the second portion of the flexible circuit may bepositioned between the electrode and the receiving means, when theelectrode is positioned in the receiving means. This provides a bettercontact between the flexible printed circuit and the electrode, as theflexible printed circuit is shaped according to the form of theelectrode and the receiving means and thereby provides a larger area ofcontact.

The receiving means may be a bushing. The bushing is a preferredreceiving means and is easily formed in the main housing part. Thebushing may be provided in various shapes, such as conical, pyramidshaped etc.

A tapered form of the bushing on its inner side makes it possible to usevarious sizes of electrodes and at the same time securing a large areaof contact with the flexible circuit. This is i.a. advantageous whenusing electrodes of slightly varying transverse dimensions.

The electrosurgical pencil may further comprise a suction channel. Thesuction channel may be provided along the length in the interior of thepencil. This eliminates the need for any external suction devices as thesmoke generated by using the electrosurgical pencil may be hazardous. Byintegrating the suction channel into the pencil the pencil is morecomfortable to work with and provides a better view for the surgeon ofthe operation site.

In a preferred embodiment, the exterior of the electrosurgical pencilhas a substantially triangular shape. By giving the pencil asubstantially triangular shape a good grip and good ergonomics areprovided. Additionally, the substantially triangular shape provides abetter view of the operation site for the surgeon, as the “flat” sidesof the triangle takes up less viewing space as compared to the rim of across-sectionally circular pencil. Additionally, when suction isprovided in the pencil and a suction tube is mounted on the proximal endof the second housing part, the surgeon is less inclined to allowturning of the pencil in response to the torsional load exerted by thesuction tube when handling the pencil. With the substantially triangularshape the surgeon will automatically hold the pencil in the mostcomfortable position, where he has access to the actuators. He willthereby not be inclined to allow the pencil to turn, as he would if itwas circular.

The suction channel may have a substantially triangular shape. Thisshape makes the most use of the space available in the substantiallytriangular shape of the exterior of the pen. If a circular suctionchannel was provided the suction volume would be substantiallydecreased.

The substantially triangular shape may be defined by the area ratiobetween a first triangle which circumscribes the substantiallytriangular shape and a second triangle inscribed in the substantiallytriangular shape, which area ratio preferably is between 1:1 and 3:1.This ratio provides a shape that possesses sufficient properties as tooptimum use of space and still lies comfortably in the hand.

A radius of curvature in at least one corner of the substantiallytriangular shape may be between 1 mm and 5 mm, preferably between 2 mmand 4 mm. By having rounded corners, provided by this radius ofcurvature, there are no sharp edges, while at the same time thetriangular shape is still present.

The flexible circuit may comprise at least a partial gold coating forcreating a contact between the electrode and the flexible circuit. Byusing gold, a better contact between the electrode and the flexiblecircuit is obtained and the gold does not corrode.

The electrosurgical pencil may comprise a main housing part, providedwith at least one indentation adapted to receive a corresponding switch.One or more indentations may be provided in correspondence with thenumber of switches. By providing the housing with an indentation, theswitch cannot shift and the switch or switches cannot be seen or felt asbumps on the outside of the housing.

The electrosurgical pencil may comprise a second housing part, providedwith a guide recess for receiving a cable. The recess makes it easier toinstall the cable as it is easier to slide the cable into a recessending in a hole than it is to simply put the cable through a holewithout any guiding means. The recess additionally provides support forthe cable when mounted.

A first housing part, attachable to a main housing part, may be providedwherein the first housing part may comprise a slit adapted to engagewith the flexible circuit. The slit is both adapted to engage with theflexible circuit as well as with the first support member, keeping theflexible circuit in a correct position with respect to the main housingpart.

Any of the first, second and main housing parts may be adapted to beassembled crosswise. By assembling the parts this way, the manufactureand assembly operations are facilitated.

In a second aspect of the invention, a kit of parts is provided. The kitcomprises an electrosurgical pencil as defined, a tube, a cable, and aconnector. This makes it possible to provide the parts necessary forcarrying out the surgical operation or operations desired.

Preferably, the tube is attachable to a proximal end of theelectrosurgical pencil, the cable is connected to the electrosurgicalpencil and extends through the tube and the connector is attachable atthe distal end of the tube, wherein the connector is provided with acable recess for guiding the cable out of the tube. This provides for asecure and reliable design, which is furthermore easy to handle.

In a preferred development of this embodiment of the kit, a suctionchannel is provided in the tube and the cable is separated from thesuction channel by a partition wall in the tube, which enhances thesecurity and ease of operation even further.

According to third and fourth aspects of the invention, a method ofassembling an electrosurgical pencil and a kit of parts, respectively,is provided.

The terms first, second and main housing parts do not indicate anyspecific configuration, order or position of the housing parts. Theparts may be positioned in a different order, such that for example themain housing part is actually positioned at the most distal end of thepencil.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in further detail withreference to the drawings, where

FIG. 1 is a perspective view of an electrosurgical pencil according tothe invention,

FIG. 2 is a vertical cross sectional lengthwise view,

FIG. 3 is an exploded view of an electrosurgical pencil according to theinvention,

FIG. 4 is a cross sectional crosswise view,

FIG. 5 is a horizontal cross sectional lengthwise view,

FIG. 6 is a perspective view of parts of the housing,

FIGS. 7a-7b are perspective views of a second embodiment of anelectrosurgical pencil according to the invention,

FIG. 8 is an exploded view an electrosurgical pencil according to theinvention,

FIGS. 9 and 9 a-9 b are vertical cross sectional lengthwise views, wherethe respective ends of the device have been magnified in FIGS. 9a -9 b,

FIGS. 10a-10d are different views of the connector,

FIGS. 11a-11b are different views of the connector with a cable mounted,

FIG. 12 is an example of the triangular shape of the pen,

FIGS. 13a-13c show a second embodiment of a detail of an electrosurgicalpencil according to the invention in a non-extended position,

FIGS. 14a-14c show a second embodiment of the detail of theelectrosurgical pencil of FIG. 13, where the electrode is in an extendedposition,

FIGS. 15a-15c show a second embodiment of the detail of theelectrosurgical pencil of FIG. 13 in another position,

FIGS. 16a-16b shows a second embodiment of an extension device in aperspective view and a cross sectional view, respectively,

FIG. 17 shows the pencil with a second embodiment of the second housingpart 6,

FIGS. 18a-18b show the pencil as seen in FIG. 17 with a tube connectedthereto,

FIGS. 19a-19e show a third embodiment of the electrosurgical pencil inthree different positions and two cross sectional views, respectively,

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-6 represent a first embodiment and parts thereof. FIGS. 7-9 showa kit of parts where further features have been added to the firstembodiment. FIGS. 10a-d and 11a-b show a connector which is a part ofthe kit of parts. FIG. 12 show an example of a substantially triangularshape and it shows how this is defined.

When referring to the respective ends of the different parts of thepencil and the kit of parts, the end closest to the opening forreceiving the electrode is referred to as the distal end of each part,while the opposite end is referred to as the proximal end for each part.

One embodiment of a pencil according to the invention is shown in FIGS.1-6. Here, the pencil 100 is in an assembled state, in which theindividual parts and elements are mounted. As seen from the outside thepencil comprises two actuators 71, here in the form of buttons, but itmay also be rocker buttons. In the embodiment shown, the pencil 100further comprises a sheath 7 in a soft and or resilient material such assilicone or rubber. Additionally, the pencil 100 comprises a firsthousing part 5 and a second housing part 6. An electrode 1 is projectingfrom the first housing part 5. As will be described in further detailbelow, the pencil 100 has a substantially triangular shape with roundedcorners. The housing parts are adapted to be assembled crosswise but mayalso be assembled lengthwise, or configured in any other manner.

The first embodiment of the invention will now be described withreference to FIGS. 2-5. In addition to the features discloses in FIG. 1the pencil may additionally comprise an electrode 1.

The electrosurgical pencil 100 may be reusable and the electrode 1disposable. The pencil may also be disposable. The disposable versionmay have an electrical cable embedded in a suction tube positioned atthe end of the suction channel of the pencil. The reusable pencil mayhave the electrical cable attached to the end of the pencil however thecable may be positioned outside the suction tube.

The part of the electrode 1 adapted to be mounted in the receiving means41 is between 2.2 and 2.6 mm in diameter. The overall cross-sectionaldimensions of the electrode may be between 1-3 mm in diameter. Theelectrode 1 is adapted to be mounted in a bushing or other receivingmeans 41 of the main housing part 4.

The electrode may be selected from the group consisting of a bladeelectrode, a needle electrode, a ball electrode, a conization electrode,a loop T-bar electrode, an arthroscopic electrode, an electrodeextender, all of them with or without non-stick coating. This ensuresthat the pencil can be used for a variety of purposes.

In the embodiment shown, the housing generally designated 4,5,6,7comprises the first, second and main housing part 4,5,6 and the sheath7. The electrosurgical pencil may consist of a housing, a flexiblecircuit, an electrode receiving means and a switch, wherein the pencilis adapted to be connected to a cable and an electrode.

The housing parts 4,5,6 and parts of the kit of parts, including tube 9and a connector 10, are made from any suitable material or polymer, suchas ABS, PSU, high density polymer (HDPE) or low density polymer (LDPE),or polyvinylchloride (PVC). The housing is free from phthalates, but mayalso be made in a phthalate containing material.

The transverse dimension 350 of the housing 4,5,6,7 is around 14.5 mmmeasured from a corner of the substantially triangular shape, to theopposing side, at the widest point. The overall dimension of the housing4,5,6,7 may be slightly larger, such as less than 16 mm, or less than14.5 mm, such as 12 mm, measured from a corner of the substantiallytriangular shape, to the opposing side, at the widest point.

The length of the pencil 100 is less than 15.5 cm. The pencil may alsobe longer such as less than 20 cm, or less than 17 cm.

The weight of the pencil 100 is 14 g. The pencil 100 may be heavier andweigh less than 16 g, or less than 18 g.

The housing 4,5,6,7 may be formed in one piece or the second housingpart 6 and main housing part 4 may be formed in one piece, or the firsthousing part 5 and the main housing part 4 may be formed in one piece.The first housing part 5 is adapted to slide into the main housing part4 forming a fluid tight seal between the two.

The second housing part 6 is adapted to slide into the main housing part4 forming a fluid tight seal between the two. The second housing part 6is further provided with a compartment 61 adapted to accommodate the endof the first portion 21 of the flexible circuit 2. The compartment 61 isseparated from the suction channel 8.

The second housing part 6 is additionally provided with a guide recess62 for receiving an electric cable. At the bottom of the recess thesecond housing part 6 is provided with an aperture, such that the cablecan be connected with the flexible circuit 2 inside the housing. Thefirst portion of the flexible circuit 21 extends into the second housingpart 6 from the main housing part 4. The space 61 for the cable insidethe second housing part and for the flexible circuit 2 is separated fromthe suction channel 8.

The first housing part 5 is hollow and tapered at the distal end and hasan aperture from which the electrode projects. The first housing part 5is triangular in shape and has rounded corners. The triangular shapemakes the tip of the pen comfortable to hold, which is particularlyuseful when doing child surgery or other fine surgery that require alarge degree of precision. In this case the surgeon will often hold thedistal end of the pen. The pencil may be controlled via a foot pedalinstead of via the actuators, as a more steady hand may be required. Itmay also be other shapes such as circular or have sharp corners. It isfurther provided with a first slit 51 and a second slit 52 at theproximal end. The slits are positioned directly opposite each other. Theslits 51, 52 may be positioned elsewhere along the edge of the firsthousing part.

The first and the second housing parts are provided with notches 55, 65,which, in an assembled state, define a shore area there between, wherethe sheath 7 is positioned.

The main housing part 4 has a triangular shape with rounded corners. Itmay also be other shapes such as circular or have sharp corners. Themain housing part 4 comprises receiving means 41, in form of a bushing,which is tapered. The receiving means 41 may be straight, conical,pyramid shaped or polygon shaped or be circular at the opening of thereceiving means and polygon shaped at the bottom of the receiving means41 or vice versa. The top of the aperture of the receiving means 41where the flexible circuit enters the receiving means is rounded,meaning that in a cross section of the pencil an exterior circumferenceof the receiving means is circular. The flexible circuit is therebycurved cross-wise in the point where it is folded, and enters thereceiving means. In a cross-section of the pencil an exteriorcircumference of the receiving means may be flat on the top, howeverkeeping its shape of the interior circumference. A wedge segment mayhave been removed from the top of the opening of the receiving means.This removes the stress on the flexible circuit, that in this specificpoint is bent around 180 degrees and by flattening the top of theopening, the flexible circuit is only bent in one plane instead of two,as a circular exterior circumference of the receiving means requires theflexible circuit to adapt to the curved shape of the receiving means.

The receiving means 41 is positioned in the center at the distal end ofthe main housing part 4 facing the first housing part 5. The receivingmeans 41 may also be in the form of a number of rings for supporting theelectrode 1 or a number of bars or rods running in parallel to theelectrode 1. The receiving means is made of plastic and/or is cast inone with the main housing part 4.

A first support member 44 is provided at the distal end inside the mainhousing part 4. The first support member 44 is retracted from the edgeof the distal end of the main housing part 4. It functions both as asupport for the receiving means 41 and it functions as a stopper for thefirst housing part 5 when this is slid into an assembled position. Whenassembled, the crease of the flexible circuit 23 is positioned betweenthe support member 44 and the edge of the first housing part 5. A firstslit 51 in the first housing part is adapted to engage with the flexiblecircuit 2 as well as with the first support member 44. The secondportion of the flexible circuit 22 is adapted to engage with the firsthousing part 5 and is therefore narrower than the first portion of theflexible circuit 21, as the second portion is adapted to enter thereceiving means and have to adapt to the shape electrode.

A second support member 43 is provided opposite the first support member44. When assembled the second support member 43 engages with the secondslit 52. The second support member also provides support for thereceiving means 41.

One or more indentations 42 are provided along the length of the mainhousing part 4. These indentations 42 are used to accommodate theswitches 3 in order to keep the pencil slim.

The interior of the main housing part 4 surrounding the receiving means41 forms a suction channel 8, which extends through the first housingpart 5, main housing part 4 and the second housing part 6. The suctionchannel 8 is used to evacuate smoke and aerosols and particles from thesurgical site. The suction channel 8 within the housing parts 4, 5, 6has in the embodiment shown a substantially triangular shape 330. Thesuction channel may also have other shapes, such as a circular shape.

The flexible circuit 2 comprises a first portion 21 and a second portion22 and a middle crease 23. In the embodiment shown, the first portion ofthe flexible circuit is 67 mm long, 7.5 mm wide and around 0.14 mmthick. This corresponds to a volume of approximately 70 mm³. The secondportion is about 37 mm long and 2 mm wide and 0.14 mm thick. The secondportion is cut out of the first portion of the flexible circuit and doestherefore not add to the volume. By cutting the second portion out ofthe first portion of the flexible circuit a smaller, and square shaped,circuit may be produced and less waste may be generated duringproduction. The second portion of the flexible circuit may be othersizes and it may be produced separately from the first portion. Thefirst portion comprises the control structure while the second portion22 is adapted to connect with the electrode 1 in the bushing 41. Theflexible circuit 2 is of a paper thin flexible material, such as a foil,with a control structure printed upon it. When mounted the flexiblecircuit 2 is folded as shown on the figure with three creases. Whenassembled the first crease abuts against the edge of the receiving means41, the middle crease 23 abuts against the bottom of the first slit 53of the first housing part 5 and the second crease abuts against the edge46 of the main housing part 4. The flexible circuit 2 may be arranged inother ways, such that there for example is only one crease. The flexiblecircuit may also be folded more times or it may not be folded at all.

The flexible circuit may be selected from the group consisting of aflexible circuit board, a flexible printed circuit and flexible printedcircuit board.

The second portion 22 is substantially parallel to the first portion 21,when mounted in the receiving means 41 of the housing 4,5,6,7. This isachieved by folding the flexible circuit 2 approximately 180 degrees.However, in the mounted position when the second portion of the flexiblecircuit is in the receiving means, the angle is slightly less than 180degrees, which can be seen from FIG. 8. But the two portions 21, 22 arestill even in this position, substantially parallel. Several foldingsmay be used to achieve the same effect. The first portion of theflexible circuit may be positioned between the actuator 71 or button andthe switch 3. The flexible circuit is provided with a gold coating, on apart of the second portion 22 of the flexible circuit 2. It may also beprovided with another conducting coating such as silver, copper or tin.The flexible circuit is to a great extent covered by a film, such thatthe conducting parts are not exposed. However, on the second portion ofthe flexible circuit 22, this foil is not present, at least on one side,and the conducting part of the circuit is therefore be in direct contactwith the electrode 1, when the electrode 1 is in the receiving means 41.At least a part of the second portion of the flexible circuit 22 is tobe positioned between the electrode 1 and the receiving means 41, whenthe electrode 1 is positioned in the receiving means 41. In FIG. 4 itcan be seen how the second portion 22 of the flexible circuit is shapedaccording to the shape of the electrode 1, such that an optimal contactis obtained between the second portion of the flexible circuit 22 andthe electrode.

A sheath 7 made of a resilient material, such as silicone or rubber,encloses mainly the middle part 4. It isolates the flexible circuit,which is the only conducting part connecting the electrode with thecable, from the user. Additionally, it provides the actuators/buttons 71from where the user can control the activation of cutting andcoagulating power from the generator. The suction may be controlled viathese buttons as well. The sheath 7 is adapted to snugly fit the mainhousing part 4 with the flexible circuit 2 and the switches 3 inposition for use. The thickness of the sheath 7 is greater than 0.35 mmin the area covering the switch 3. The sheath 7 may be expended with andinstead a non-resilient housing part may used. This part may in turn beprovided with apertures in which buttons may be positioned foractivating the pencil.

The pencil further comprises two micro switches 3. The switches 3 formpart of the switching means. Other switches that may be used include adome, a metal dome switch, a metal tactile switch, a membrane switch ora membrane keypad. The switches 3 are attached to the flexible circuit2. The switches 3 are positioned between the flexible circuit 2 and themain housing part 4. The switches 3 are positioned upside down such thatwhen the user presses the button, he actually pushes on the back of theswitch. This is possible because the flexible circuit is so thin thatthe flexible circuit 2 flexes and thereby does not simultaneouslyactivate both switches. If a non-flexible circuit had been used, thepressure on the button would have activated both switches. The flexiblecircuit 2 thereby makes it possible to activate the switch from the backside. It is thereby the resistance of main housing part that activatesthe switch. In this way there is no exposed circuit facing towards theactivator 71. Thereby two layers of insulation from the circuit areprovided in the form of the sheath 7 including the activators 71 and theflexible circuit 2, which does not have any conducting parts on the facefacing the sheath 7. The volume of the flexible circuit 2 and theswitches 3 is minimal and takes up less than 0.15 cm³ of space. Thevolume of one switch is less than 35 mm³. The conducting part and theswitch may be sized such that the volume of the two parts is less than0.5 cm³ or less than 0.3 cm³. The switch may be less than 60 mm³, orless than 40 mm³. This small volume maximizes the space for a possiblesuction channel within the housing.

This means that the volume of an optional suction channel 8 is optimizedas the only remaining parts are the housing and the means for supportingand receiving the electrode.

When using a flexible circuit 2 and micro switches 3 or small switchesin general, the electrode 1 may extend beyond the most distal switch 3,such that the distance from the tip of the electrode to the actuatorpositioned on top of the switch is minimized. When doing surgery, theactuators will be close to where the surgeon's fingers are positionedand thereby he will not have to rearrange the pen in his hand to reachthe actuators.

When one of the buttons 71 is pressed down, the first portion of theflexible circuit 21 is adapted to flex and the switch 3 is pressedagainst the indentation 42 in the main housing part 4. A signal is sentto the control structure on the flexible circuit 2 and the electrode 1is activated. When the button 71 is pushed down the user may hear aclicking sound or feel a tactile feedback such that the user is awarethat the pencil has been activated.

When the pencil 100 is in use, it is connected to a generator (notshown), by a cable 11. The patient is provided with a grounding platesomewhere on the body. The electrode thereby forms one pole and thepatient forms the other. The generator to which the pencil is connectedto delivers power with a frequency of minimum 350 kHz.

The kit of parts in FIGS. 7-9 comprises an electrosurgical pencil 100, atube 9, a cable 11 and a connector 10. The kit may comprise any otherfeatures as disclosed in the first embodiment. Each of the features isindependent of each other unless explicitly stated so, and may thereforebe added to the kit independently of each other. The tube 9 is adaptedto be mounted on the second housing part 6 at the proximal end. Thesecond housing part 6 is provided with one or more projections forretaining the tube 9, such the tube 9 can be securely mounted. The tube9 is made in a plastic material. The tube 9 may function as a suctionchannel for guiding smoke, aerosols and particles to a container forcollection. The tube is therefore connected to the suction channel 8.The tube 9 may furthermore be used for guiding the cable such that itdoes not get in the way when the surgeon works. At the proximal end ofthe tube 9 a connector 10 may be mounted. The connector 10, such as asplicing sleeve, is made in a polymer material. It is provided with acable recess 101 such as the one provided in the second housing part 6,and is used for guiding the cable 11 to the exterior of tube 9. A sealthat is sufficiently tight such that no particles can escape is providedbetween the cable 11 and the connector 10. The cable is provided withinthe suction channel. The cable 11 may be separated from the suctionchannel in the tube 9 by a partition wall. Such a separation providesthe possibly to makes the electronic pencil reusable, along with furtherfeatures. The connector 10 may be provided with barbs 63 as seen in FIG.17. Further views of the connector 10 is shown in FIG. 10a-d and with acable mounted, in FIGS. 11a -b.

FIG. 12 shows an example of the substantially triangular shape. Thesubstantially triangular shape has the advantages that it is easier forthe surgeon to see the tip of the electrode during surgery, as acircular shaped housing would be blocking some of the view that thesubstantially triangular shape exposes instead. The rounded corners ofthe triangle are defined by the radius of curvature R1. The radius ofcurvature is 2 mm at the distal end of the first housing part 5 andaround 4 mm at the proximal end of the second housing part 6 at thewidest point. The radius of curvature may vary locally. The sides of thesubstantially triangular shape are also defined by a radius of curvatureR2. This is 8 times larger than R1 in any cross section of the penciland provides a less curved line. It may also be from 3 to 10 timeslarger or merely a straight line. The substantially triangular shape 330cuts through the corners 340 of the second equilateral triangle 320. Thetriangles 310, 320 are positioned with the second equilateral triangle320 within the first equilateral triangle 310 such that their sides areparallel.

In the embodiment shown, the substantially triangular shape is definedby the area ratio between a first triangle 310 which circumscribes thesubstantially triangular shape and the second triangle 320 inscribed insaid substantially triangular shape, is between 1:1 and 3:1. A ratioapproaching 1:1 means that the substantially triangular shape is in factvirtually triangular including straight lines between the respectivecorners of the triangle. In the other end of the interval, the ratio 3:1provides for a satisfying grip due to the curved outline. In theembodiment shown, the ratio is approximately 2.34.

The substantially triangular shape may be seen in only some or parts ofthe housing parts, such as the first, second and main housing parts,where the remaining parts may have a substantially circular shape. Thedistal end of the first housing part 5 may have a substantiallytriangular shape, while the proximal end of the first housing part 5 mayhave a substantially circular shape or vice versa. The housing may haveany other cross-sectional shape.

In FIGS. 13a-c, 14a-c, and 15a-c , an embodiment of an extension deviceis shown. Each of the FIGS. 13-15 shows a lengthwise cross sectionalview, a, a lengthwise cross sectional perspective view, b, and aperspective view, c, in three different positions of extension.

The extension device 300 comprises an extender 50. It is usable foreither extending the suction channel and/or extending the electrode. Theextender 50 is adapted to be positioned on the first housing part in thefirst embodiment. The first electrode extender is provided with areceiving means for the second electrode extender 112. The receivingmeans may be in the form of a bushing.

The extender 50 comprises a first extender part 501 and a secondextender part 502. The first extender part 501 is adapted to slide inthe second extender part 502. The second extender is tapered at thedistal end. The second embodiment further comprises a first electrodeextender 111 and a second electrode extender 112. The second electrodeextender 112 is adapted to slide in the first electrode extender 111.The electrode 1 is positioned in the second electrode extender 112, butmay be separate there from. The first and second electrode extenders aremade of a conducting material. The first electrode extender 111 isadapted to be positioned in the receiving means 41 in the firstembodiment. The second electrode extender 112 may project from theopening in the second extender part 502 when in the most retractedposition.

In order to keep the second extender 502 and/or the second electrodeextender 112 in the selected position, the fit of the first extender 501and the first electrode extender may be sufficiently tight such thattheir respective positions are kept during an operation.

The second extender 502 and the second electrode extender 112 may bepositioned in any position between the most retracted and most extendedposition. They may keep this position during an operation or the surgeonmay adjust the position of the respective parts during the operation.

In FIG. 13 both the extender 50 and the electrode extender parts 111,112 are in a non-extended position, such that the second extender 502and the second electrode extender 112 are retracted as far back aspossible and provides the shortest possible extender 50 and electrodeextender parts 111, 112.

In FIG. 14 the extension device 300 is in an extended state. Here thesecond electrode extender 112 is positioned in its most extendedposition. The extension of the electrode may be used for reaching hardto reach places in the body, where the suction channel or secondextender part 502 are not serving a purpose or are getting in the way,respectively.

In FIG. 15 the second electrode extender 112 and the second extender 502are positioned in their most extended position. Here, if an extra longpencil and suction are required, this position serves both purposes.

The extension and retraction of the respective parts are performed bypulling and pushing the second parts 112 and 502, respectively.

Any parts of the second embodiment 300 may be combined with any parts ofthe first embodiment 100. In particularly the extension device 300 maybe positioned as an extension on the first housing part 5. The firstelectrode extender 111 may be positioned in the receiving means 41,thereby creating an electrosurgical pencil with a telescopic suctionchannel and a telescopic electrode.

FIGS. 16a-b show a second embodiment of an extension device in aperspective view and a cross sectional view, respectively. Here anelectrode extender 212 is comprised in a separate extension piece 510.The extension piece 510 comprises a pipe piece 511 and an electrodeextender 212. The pipe piece 511 is made of a transparent material, suchthat it is easier for the surgeon to see, what he is working with, asthe pipe piece 511 doesn't block his view. The pipe piece 511 is madefrom plastic or other material that will not show on an X-ray picture.However, the electrode extender 212, which is made of a conductingmaterial, such as metal, and which extends through the length of thepipe piece 511, will show on an X-ray picture, in case the extensionpiece 510 should be lost in a patient. Additionally, or alternatively,the pipe piece 511 may be made of other materials for example a polymercomprising barium sulfate. The barium sulfate makes the pipe piece 511visible on an x-ray picture.

The extension piece 510 is adapted to be attached to an electrosurgicalpencil of any of the other embodiments. The pipe piece 511 is adapted tobe attached to the first housing part 5 and the electrode extender 212,which is provided inside the pipe piece 511, is adapted to be positionedin the receiving means 41 of the pencil as seen on the precedingembodiments. When the extension piece 510 is pushed onto the pencil, theelectrode extender 212 is connected to the flexible circuit and a stableelectronic connection is created. At the distal end of the electrodeextender 212, the electrode may be positioned. Because an electrodeextender 212 is used, there is no need to used different lengths ofelectrodes, and the surgeon may therefore use the same electrode nomatter the required length of the pencil.

Additionally, the extension piece 510 is adapted to be positioned onanother extension piece 510, making the pencil even longer, which isparticularly useful when operating on larger patients. The extensionpiece 510 thereby fits onto itself. So instead of having to storedifferent lengths of extender pieces, only one kind of extension pieceis needed for providing different lengths. When a second extension piece510 is attached to first extension piece 510, the electrode extender 212of the first extension piece is pushed to a side such that theoverlapping lengths of each electrode extender merely abut each other.Alternatively, each end of the electrode extender 212 may be formed as aplug and a socket, as seen in FIG. 13.

The electrode 1 is further provided with an insulation sheath 513, forholding on to the electrode 1 when inserting or removing electrode 1from the pencil. The insulation sheath 513 may be dispensed with.

FIG. 17 shows a second embodiment of the second housing part 6. Thesecond housing part 6 has here been provided with barbs 63. One or morebarbs 63 may be provided. This is to ensure that the tube (not shown)conveying the material sucked from the patient's body is properly fixed.The tube is simply pushed over the barbs and as the material of the tubeis slightly expanded where the barbs are positioned inside the tube, thetube stays fixed, but may be removed from the pencil by pulling thetube. The tube is, as in the previous embodiments, able to rotate aroundits axis. The tube may also be fixed such that it is unable to rotate.The cable providing the pencil with power may be positioned inside oroutside the tube.

FIGS. 18a-b show the embodiment in FIG. 17 with a tube mounted directlyon the pencil. Because the second housing part 6 is provided with barbsas seen in FIG. 17, it is possible to mount the tube directly on thepencil and the connector, as seen in FIGS. 8-10, can be dispensed with.

FIGS. 19a-c show a third embodiment of the electrosurgical pencil 400 ina non-extended position and in a position with an extended first housingpart and in a position with an extended electrode 1, respectively. Whatdiffers from the embodiment in FIG. 2 is that the flexible printedcircuit 2, comprising a first portion 421 and a second portion 422, islonger. The first housing part 35 is also longer compared to the housingpart in FIG. 2. The first housing part 35 is adapted to slide insidemain housing part 4, such that the user is able to telescopically toextend the pencil 400 as seen in FIG. 19b . When the user pulls thefirst housing part 35, the electrode 1 and the flexible printed circuit2 will follow. The flexibility of the flexible printed circuit 2 is usedsuch that the flexible printed circuit 2 remains in contact with boththe electrode 1 and the switching means 3. The pencil 400 is providedwith a locking means (not shown) such that it may be impossible to pullthe first housing part 35 completely out of the pencil 400.

Because the sheath 7 is made of silicone or a similar material, there isfriction between the first housing part 35 and the sheath 7, which keepsthe first housing part 35 in position during use. Another means forcreating friction between the two may be used. Friction means may alsobe provided between the main housing part 4 and the first housing part35.

In addition to the above mentioned differences the electrosurgicalpencil 400 further differs from the embodiment in FIG. 2 in that it isprovided with sliding means making possible to extend the electrode 1from the first housing part 35 as seen in FIG. 19c . The sliding means451, 443 can clearly be seen in FIG. 19d . This feature is particularlyuseful when the surgeon is operating in deep cavities. The first housingpart 35 is provided with sliding means comprising a guide 451. The firsthousing part 35 accommodates an element, which element comprises thesupport member 443 and 444 and the receiving means 41 for holding theelectrode 1. The sliding means also comprises a support member 443,which is adapted to slide in the guide 451. The extension of theelectrode 1 is accomplished by pulling the electrode 1, which remain inthe receiving means 41 and in contact with the flexible printed circuit2 while being extended from the first housing part 35. In order todetach the electrode 1 from the receiving means 41, the electrode 1 mustbe turned first.

A cross section of the embodiment of the electrosurgical pencil 400 canbe seen in FIGS. 19d and 19e . The cross section in FIG. 19e isindicated on FIG. 19a by the line X1-X2.

Like parts in each of the several figures are identified by the samereference. Any feature from any embodiment may be combined with eachother independently of other features and no feature is essential unlessexplicitly mentioned in the claims. When referring to a pen, pencil orelectrosurgical pencil, we are referring to an electrosurgical pencil.

What is claimed is:
 1. Extendable electrosurgical pencil (400) adaptedto receive an electrode (1) controllable by an electrical signal forperforming surgical operations, comprising: a housing that comprises afirst housing part (35) and a second housing part (6), and a mainhousing part (4) between the first housing part (35) and the secondhousing part (6), a flexible printed circuit (2), switching means (71)on the main housing part (4) of the housing and being adapted to beactivated from outside the housing for closing the flexible circuit (2),and the first housing part (35) comprises receiving means (41) forreceiving the electrode, wherein the first housing part (35) is adaptedto slide inside the main housing part (4) to provide a telescopicextension of the pencil (400), the electrode (1) and the flexibleprinted circuit (2) following the sliding movement.
 2. Electrosurgicalpencil (400) according to claim 1, wherein the first housing part (35)of the electrosurgical pencil (400) has sliding means (451,443) totelescopically extend the electrode (1) from the first housing part(35).
 3. Electrosurgical pencil (400) according to claim 2, wherein thesliding means comprises a guide (451) and a support member (443), whichis adapted to slide in the guide (451).
 4. Electrosurgical pencil (400)according to claim 3, wherein the first housing part (35) accommodatesan element, which element comprises the support member (443) and (444)and the receiving means (41) for holding the electrode (1). 5.Electrosurgical pencil (400) according to claim 2, wherein extension ofthe electrode (1) is accomplished by pulling the electrode (1), whichremain in the receiving means (41) and in contact with the flexibleprinted circuit (2) while being extended from the first housing part(35).
 6. Electrosurgical pencil (400) according to claim 1, wherein theflexible printed circuit (2) is of a paper-thin flexible material havinga control structure printed upon it, wherein the flexible printedcircuit (2) remains in contact with both the electrode (1) and theswitching means (3).
 7. Electrosurgical pencil (400) according to claim6, wherein the paper-thin flexible material is a foil. 8.Electrosurgical pencil (400) according to claim 1, wherein theelectrosurgical pencil (40) is provided with a locking means such thatthe first housing part (35) cannot be pulled completely out of theelectrosurgical pencil (400).
 9. Electrosurgical pencil (400) accordingto claim 8, wherein the sheath has a thickness that is greater than 0.35mm in the area of the switching means.
 10. Electrosurgical pencil (400)according to claim 1, wherein the switching means (3,71) comprises aswitch (3) and an actuator (71).
 11. Electrosurgical pencil (400)according to claim 10, wherein the first portion of the flexible printedcircuit (21) is positioned between the actuator (71) and the switch (3).12. Electrosurgical pencil (400) according to claim 1, wherein theelectrosurgical pencil (400) further comprises a suction channel alongthe length in the interior of the pencil (400).
 13. Electrosurgicalpencil (400) according to claim 1, further comprising friction meansbetween the main housing part (4) and the first housing part (35). 14.Electrosurgical pencil (400) according to claim 1, further comprising asheath (7) that encloses the main housing part (4).
 15. Electrosurgicalpencil (400) according to claim 14, wherein the sheath (7) is made of amaterial that provides friction between the first housing part (35) andthe sheath (7), which keeps the first housing part (35) in positionduring use of the electrosurgical pencil (400).
 16. Electrosurgicalpencil (400) according to claim 14, wherein the sheath (7) is made ofsilicone.
 17. Electrosurgical pencil (400) adapted to receive anelectrode (1) controllable by an electrical signal for performingsurgical operations, comprising: a housing that comprises a firsthousing part (35) and a second housing part (6), and a main housing part(4) between the first housing part (35) and the second housing part (6),a flexible printed circuit (2), switching means (71) on the main housingpart (4) of the housing and being adapted to be activated from outsidethe housing for closing the flexible circuit (2), and the first housingpart (35) comprises a receiving means (41) for receiving the electrode,wherein the first housing part (35) is adapted to slide inside the mainhousing part (4) to provide a telescopic extension of the pencil (400),the electrode (1) and the flexible printed circuit (2) following thesliding movement, and wherein the flexible printed circuit comprises afirst portion (21) and a second portion (22), wherein the second portion(22) is folded substantially parallel to the first portion (21), whenmounted in the housing, wherein the second portion of the flexibleprinted circuit (22) extends into the receiving means (41) of thehousing.
 18. Electrosurgical pencil (400) adapted to receive anelectrode (1) controllable by an electrical signal for performingsurgical operations, comprising: a housing that comprises a firsthousing part (35) and a second housing part (6), and a main housing part(4) between the first housing part (35) and the second housing part (6),a flexible printed circuit (2), switching means (71) on the main housingpart (4) of the housing and being adapted to be activated from outsidethe housing for closing the flexible circuit (2), and the first housingpart (35) comprises a receiving means (41) for receiving the electrode,wherein the first housing part (35) is adapted to slide inside the mainhousing part (4) to provide a telescopic extension of the pencil (400),the electrode (1) and the flexible printed circuit (2) following thesliding movement, and wherein the exterior of the electrosurgical pencil(400) has a substantially triangular shape defined by the area ratiobetween a first triangle (310) which circumscribes said substantiallytriangular shape and a second triangle (320) inscribed in saidsubstantially triangular shape, is between 1:1 and 3:1. 19.Electrosurgical pencil (400) according to claim 18, wherein at least onecorner (340) of the substantially triangular shape (330) has a radius ofcurvature that is between 1 mm and 5 mm or that is between 2 mm and 4mm.